Cutting clip causes audio to overlap

I'm a newcomer to FCPX, but I think I've found a bug in 10.0.5. It exists in 10.0.3 and 10.0.4, the other two versions I have tried.

I am using FCPX to edit screencasts. I record my screen and microphone using SnapzProX and import the clip into FCPX in order to remove unwanted sections. The bug I think I've found is that under certain circumstances, when I cut a portion of a clip out, significant portions of the audio track will get overlapped. I'm not talking about a few frames; depending on the size and location of the cut, it could be a few seconds or even dozens of seconds of audio that get overlapped.

First, here's how it's supposed to work:

1. Start a new project and import a longish clip (mine are a few minutes in length). Add the clip to the project.
2. Using the I and O keys, select a portion of the clip and cut it using the Delete key. Do this a few times. Now the clip is broken up into multiple shorter clips.
3. Add Cross Dissolve transitions to the cuts.
4. Watch and listen to the whole project. It should be OK.

Now we'll replicate the bug:

1. Start a new project and add the same clip to the new project.
2. Expand the audio and video tracks using ^S or right-click on the track and selecting the "Expand Audio/Video" menu item.
3. Cut out a few portions of the clip using the I/O keys and Delete.
4. Watch the project. It should still be OK.
5. Add a single cross dissolve transition somewhere in the timeline.
6. Use the I/O keys to select a portion of the clip that's adjacent to the transition you just added. Delete it.
7. You should see the audio tracks get overlapped.

You can also cause the bug with the blade tool:

1. Do steps 1-5 above.
2. In the clip adjacent to the transition, use the blade to place a cut in the clip.
3. You should see the audio tracks get duplicated.
4. Make another blade cut.
5. Select the sub-clip you just created and delete it using the Delete key.
6. Notice that the audio gets overlapped just like it did using the I/O keys.

The key steps seem to be expanding the audio/video AND adding the cross dissolve to the timeline. Until you do that, everything works fine. But as soon as you add a transition to a clip whose audio and video have been expanded, you get the overlapping audio.

Here are three workarounds I've found, both annoying:

1. Don't expand audio/video.
2. Don't add transitions until you are completely done editing.
3. Trim the audio track adjacent to the transition. All you need to do is trim it a tiny bit -- a frame or two. Then cut out the desired portion of the clip as before. The audio won't get overlapped at all.

Is this a known problem?